Megachile (Cressoniella)

Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Megachilini
Genus: Megachile Latreille, 1802
Subgenus: Cressoniella Mitchell, 1934
Common name: none

Overview

Megachile (Cressoniella) are medium-sized bees with black integument and often with dense long hair that may or may not form pale apical bands hair on the terga (Michener 2007). They range in body length from 9–15 mm (Michener 2007; Gonzalez 2008).

Diagnostic characteristics

(modified from Mitchell 1935a; Michener 2007)

  • Female F1 is longer than the pedicel.
  • Female mandible is four-toothed, with the upper tooth truncate and often notched, sometimes giving the appearance of being five-toothed.
  • Female mandible with a complete cutting edge in the second interspace and a complete cutting edge in the third interspace.
  • Female tarsal claws with thickened, tooth-like basal setae.
  • Female T6 is straight in profile with distinct, erect hairs.
  • Male front coxa not spined.
  • Male fore tarsi are not expanded or modified.
  • Male mandible is four-toothed and lacks an inferior projection.
  • Male T6 preapical carina forming two often spine-like projections.

May be confused with

Megachile (Cressoniella) is a sister group to the subgenus Megachile (Dasymegachile), and they have species with similar sizes and hair patterns. Females are four-toothed in both subgenera, but the inner tooth of Megachile (Cressoniella) is truncate or notched, whereas it is acute in Megachile (Dasymegachile). Males of Megachile (Cressoniella) can be differentiated by their four-toothed mandibles and the lack of a spine on their front coxa.

Host associations

Megachile (Cressoniella) is known to visit plants in the families Aizoaceae, Asteraceae, Asclepiadaceae, Fabaceae, Lamiaceae, Onagraceae, and Solanaceae (Butler 1965; Raw 2007).

Nesting behavior

Megachile (Cressoniella) are leaf-cutter bees and use cut pieces of leaves to build their nest cells (Michener 2007). One species, Megachile (Cressoniella) grandibarbis, has been found nesting in old beetle burrows in dead branches and in the soil using the leaves of the genus Nothofagus to build its nest cells (Raw 2007).

Diversity

Megachile (Cressoniella) consists of twenty-one species (Raw 2007). Megachile (Cressoniella) zapoteca is the only species that occurs in the U.S. (Michener 2007; Gonzalez 2008).

Known invasives

There are no known invasives.

Distribution

Megachile (Cressoniella) ranges from Arizona in the southern U.S. south to Argentina. They are predominantly found in xeric environments, but several species are found in high altitudes within the Andes (Michener 2007; Raw 2007; Gonzalez 2008).

Distribution
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<p><em>Megachile zapoteka </em>female face, photo: Shaun Heller </p>
Megachile zapoteka female face, photo: Shaun Heller 
<p><em>Megachile zapoteka </em>female lateral habitus, photo: Shaun Heller</p>
Megachile zapoteka female lateral habitus, photo: Shaun Heller
<p><em>Megachile zapoteka </em>female abdomen, photo: Shaun Heller</p>
Megachile zapoteka female abdomen, photo: Shaun Heller
<p><em>Megachile zapoteka </em>male face, photo: Shaun Heller</p>
Megachile zapoteka male face, photo: Shaun Heller
<p><em>Megachile zapoteka </em>male lateral habitus, photo: Colleen Meidt</p>
Megachile zapoteka male lateral habitus, photo: Colleen Meidt
<p><em>Megachile zapoteka </em>male abdomen, photo: Shaun Heller</p>
Megachile zapoteka male abdomen, photo: Shaun Heller